1. Field of the Invention
The present invention relates to making polyols that are useful in making flexible polyurethane foams. More specifically, the present invention relates to making hybrid polyols that have a vegetable oil-based polyol segment and a petrochemical polyol segment.
2. Description of Related Art
Petrochemical polyols have been made by the polyaddition reaction of an alkylene oxide, such as propylene oxide and/or ethylene oxide, to the hydroxyl groups of liquid glycerol in the presence of a potassium hydroxide catalyst. The polyols created from such a process are branched or star polyols. One disadvantage with petrochemical polyols is that they are not made from renewable resources. Another disadvantage with petrochemical polyols is that they are not sufficiently hydrophobic so as to be useful in creating polyurethanes with good hydrolytic resistance.
Biobased-petrochemical hybrid polyols have been made by the alkoxylation of vegetable oil-based polyols in the presence of an alkaline catalyst. Specifically, alkaline catalysts, such as hydroxides and alkoxides of sodium or potassium have been used. Examples of alkaline catalysts that have been used to created biobased-petrochemical hybrid polyols are NaOH, KOH, CH3OK, and CH3ONa. One disadvantage with such current methods of making biobased-petrochemical hybrid polyols is that these alkaline catalysts split the ester bonds of the triglyceride, and the alkylene oxides are inserted between the glycerol and the fatty acid groups in addition to being added by polyaddition to the hydroxyl groups of the vegetable oil polyol. Another disadvantage of using an alkaline catalyst to create biobased-petrochemical hybrid polyols is that the reaction rate is slow and must occur at high temperatures, namely, at temperatures above 100° C. and many times above 130° C.
In order to overcome these disadvantages, a method for making a biobased-petrochemical hybrid polyol that avoids the splitting of ester bonds and that avoids the creation of side chains and that limits the formation of cyclic oligomers, such as dimers and tetramers, is needed. This process should produce polyols that are useful for making of flexible polyurethane foams.